Pass UDPAddr.Zone to net.ListenUDP

listenUDPInPortRange wasn't passing the Zone and would always fail to
bind. This would cause high CPU usage as every port in the range would
be attempted and fail.

Fixes #742

net.go

@@ -137,8 +137,13 @@ func listenUDPInPortRange(n transport.Net, log logging.LeveledLogger, portMax, p
 	portStart := globalMathRandomGenerator.Intn(j-i+1) + i
 	portCurrent := portStart
 	for {
-		lAddr = &net.UDPAddr{IP: lAddr.IP, Port: portCurrent}
-		c, e := n.ListenUDP(network, lAddr)
+		addr := &net.UDPAddr{
+			IP:   lAddr.IP,
+			Zone: lAddr.Zone,
+			Port: portCurrent,
+		}
+
+		c, e := n.ListenUDP(network, addr)
 		if e == nil {
 			return c, e //nolint:nilerr
 		}